The present invention relates to a method for controlling the driving dynamics of a vehicle, in which the steering movement is carried out as a function of a set value, which is calculated as a function of a deviation between a desired value and an actual value of a vehicle state variable.
The invention also relates to a device for controlling the driving dynamics of a vehicle with a controlling unit, which, based on the deviation of an acquired actual value of a vehicle state variable from a predetermined desired value, determines a set value, on the basis of which a steering movement is carried out.
ESP systems, which are used in cars to carry out an electronic stability program (ESP) according to the state of the art intervene for the purpose of stabilizing the vehicle in a brake system and in a combustion motor management. As a result of the interventions, yaw moments are generated in the process, which act against oversteering or understeering of the vehicle and against interfering moments which cause interfering yaw movements of the vehicle.
A block diagram of such an ESP system is shown in FIG. 1. Based on a steering angle δDrv, which is set by the driver 110 of the vehicle 150, a computer unit 120 in the process, on the basis of a vehicle reference model, determines a reference value {dot over (ψ)}M for the yaw rate of the vehicle 150. This reference value {dot over (ψ)}M is compared by a control unit 130 with an actual value {dot over (ψ)} of the yaw rate, which is acquired by the yaw rate sensor. If the difference between the actual value {dot over (ψ)} and the reference value {dot over (ψ)}M exceeds a given threshold value, then, as a function of the deviation from the rule, a set PWhlRef of wheel-specific brake pressures and a motor moment uMot are determined, and transmitted by another unit 140 as setting signals to the brake system and the combustion motor management of the vehicle 150.
In the control intervention, the current driving situation is also taken into account, which is calculated based on additional data. These data comprise, for example, the brake pressure PDrv, which is set by the driver, the set ΩWhl of the different wheel velocities, the vehicle acceleration ay and, optionally, the set PWhl of the wheel-specific brake pressures, and they allow, for example, the calculation of the vehicle velocity.
However, the brake intervention, which is carried out particularly by the ESP system, can be sensed clearly by the driver as a vehicle deceleration, and therefore, for reasons pertaining to comfort, it can be used only in the area which is critical for the driving dynamics. In the less than critical handling range, setting interventions based on the braking are acceptable only conditionally.
The motor interventions that are carried out are associated with interfering variations of the steering force, and, in addition, because their dynamics are limited as a matter of principle, they do not offer any potential at all for effectively supporting the driver in the handling range.
It has already been proposed to carry out a yaw rate control based on interventions in the steering system of a vehicle and by means of additional steering movements, which are superposed over the steering movement of the driver, to generate a yaw moment which acts against the oversteering or understeering and compensates for interfering moments.
A yaw rate control, which is based on steering interventions, here has the potential of assisting the driver, even in less than critical driving maneuvers, and thus to improve the handling as well as the agility of the vehicle.
However, the prerequisite is that the additional steering movement of the vehicle's driver is not perceived as an interference.
Therefore, the invention is based on the problem of adjusting steering interventions, which are carried out during the control of the driving dynamics, as harmonically as possible to the steering movements of the driver.